Not the worst of his offenses, but that Trump assumes all black people live one kind of life (his greater sin) and that they all live in the "inner city" really bothers me. Basically he's using "inner city" as a synonym for "urban slum" so just say that. It would still be wrong, but that's what he means. "Inner city" isn't actually a synonym for urban slum. It's a term to describe the geography of a certain kind of poverty, a poverty not just related to race (though that too), but of location, reflecting the result of history and a set of policies, along with a specific problem to be addressed. It doesn't just mean where the poor black people are. It means the "inner cities" where concentrated poverty was a big deal.
I say was, because a lot of those inner cities are doing okay. Donald Trump lives in an inner city. The geography of poverty has changed, and it's been moving out of the inner cities. Urban poverty still exists, but it's being pushed out of the inner cities to the fringes and beyond in many areas. The word "inner" is there for a reason. It meant in the center, in the core. As opposed to the "outer" city.
Also, to, he's a horrible racist who doesn't know anything about the reality of black life in America. He just thinks they all live in slums.